Timers

Timers are lightweight objects that enable you to specify a delegate to be called at a specified time. A thread in the thread pool performs the wait operation.

Using the xref:System.Threading.Timer?displayProperty=nameWithType class is straightforward. You create a Timer, passing a xref:System.Threading.TimerCallback delegate to the callback method, an object representing state that will be passed to the callback, an initial raise time, and a time representing the period between callback invocations. To cancel a pending timer, call the Timer.Dispose function.

[!NOTE] There are two other timer classes. The xref:System.Windows.Forms.Timer?displayProperty=nameWithType class is a control that works with visual designers and is meant to be used in user interface contexts; it raises events on the user interface thread. The xref:System.Timers.Timer?displayProperty=nameWithType class derives from xref:System.ComponentModel.Component, so it can be used with visual designers; it also raises events, but it raises them on a xref:System.Threading.ThreadPool thread. The xref:System.Threading.Timer?displayProperty=nameWithType class makes callbacks on a xref:System.Threading.ThreadPool thread and does not use the event model at all. It also provides a state object to the callback method, which the other timers do not. It is extremely lightweight.

The following code example starts a timer that starts after one second (1000 milliseconds) and ticks every second until you press the Enter key. The variable containing the reference to the timer is a class-level field, to ensure that the timer is not subject to garbage collection while it is still running. For more information on aggressive garbage collection, see xref:System.GC.KeepAlive%2A.

[!code-cppSystem.Threading.Timer#2] [!code-csharpSystem.Threading.Timer#2] [!code-vbSystem.Threading.Timer#2]

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Timers

See Also